The 49ers lost Dashon Goldson to the Buccaneers in free agency and signed former Rams safety Craig Dahl to help replace him. By almost any measure, Goldson is the better player (according to ProFootballFocus.com, Dahl graded out as one of the league's least effective safeties), but Dahl was part of a Rams team that gave the 49ers all they could handle last season.In Week 10, St. Louis and San Francisco played to a 24-24 tie, and three weeks later, the Rams beat the 49ers 16-13. So why were the Rams, who went 6-8 in their 14 other regular-season games, so good against the NFC's Super Bowl representative?

Dahl provided some answers Wednesday.

"We had a few tips off of film that we were able to differentiate between run and pass early," Dahl said, according to CSNBayArea.com's Matt Maiocco. "So that kind of gave us an added benefit on defense.

"It was a few different things. Some different personnel and alignment stuff really were the big keys, as far as our giveaways."

The 49ers signed Dahl to a three-year, $5.25-million deal that included $700,000 in guarantees. In that sense, he's already been worth the investment, even if he doesn't improve much on his ProFootballFocus.com rating.

"It's stuff that's been corrected," said Dahl, who had spoken to the 49ers' offensive coaches. "It's just them discussing what kind of things we prepared for when I was in St. Louis last year, as far as scouting and different things we saw game-planning against the 49ers' offense. Kind of working with the offensive coaches on that aspect, and also kind of giving them tips and tendencies on their offense.